1. Field of the Invention
The present invention relates to a car navigation apparatus capable of detecting a current position of a vehicle.
2. Description of Related Art
Car navigation apparatuses having a structure in which a storage medium such as a CD-ROM and the like is used for storing map data including road information produced by evaluating respective points on roads on maps are already known. In such apparatuses, while detecting a current position and heading direction of a vehicle, map data of a predetermined area including the current position is read from the storage medium to display a map around the current position of the vehicle on a display, and the current position and heading of the vehicle are automatically displayed.
Positioning methods used in such navigation apparatuses are generally classified into a self-contained navigation method which only uses information from sensors provided in a vehicle for measuring a variety of parameters such as a speed, heading and the like to measure a current position of the vehicle, and a navigation method relying on a navigation assisting system using GPS (Global Positioning System) (hereinafter simply called xe2x80x9cGPS navigation methodxe2x80x9d) which receives positioning data transmitted from a plurality of artificial satellites to measure a current position.
Since these two navigation methods each have their respective advantages and disadvantages, car navigation apparatuses generally employ a so-called hybrid navigation system which combines these navigation methods to compare respective measured data to perform the positioning process.
In addition, the car navigation apparatuses generally employ the so-called map matching processing for improving the accuracy of results of the positioning provided by these navigation methods and for matching the positioning results with map data, wherein if a current position of a vehicle is detected out of a road included in map data, the position is forcedly moved onto the road (for example, Japanese Patent Kokai No. 10-307037).
Since the conventional car navigation apparatuses experience difficulties in determining entry and exit of a vehicle into and from a parking area, there have been such problems as mismatching of the current position of a vehicle to a nearby road when the vehicle has entered a parking area, a delay in map matching operation upon exit from a parking area.
Such problems may be solved, for example, by building a database of map data including parking areas. However, unlike roads, parking areas are mostly managed and operated by individuals or private companies, and there are an immense number of parking areas. It is therefore extremely difficult to locate all parking areas to create a database. In addition, even if a database is once created, parking areas may often be built or demolished in a short term due to civil and construction works such as construction of buildings, land recovery, and the like, causing difficulties in correctly maintaining and managing the database.
The present invention has been made to solve the problem mentioned above, and it is an object of the invention to provide a car navigation apparatus which determines entry and exit of a vehicle into and from a parking area from a running state of the vehicle without using dedicated map data including parking areas.
The present invention provides a car navigation apparatus for determining a current position of a vehicle on map data based on at least one parameter of self-contained navigation parameters and navigation parameters received using GPS. The car navigation apparatus includes a turn-round detecting part for detecting a turn-round motion of the vehicle to generate a turn-round signal; an out-of-intersection detecting part for generating an out-of-intersection signal as long as the current position is out of an intersection; and a parking area entry determining part responsive to the turn-round signal generated when the out-of-intersection signal exists for determining that the vehicle enters into a parking area to generate a parking area entry signal.
The car navigation apparatus of the present invention may include parking area exit determining means for detecting entry of the vehicle into a road region near the current position while the parking area entry signal exists to generate a parking area exit signal.